In a Wideband Code Division Multiple Access (W-CDMA) cellular radio telecommunications system, for example as used in so-called 3rd Generation mobile communications systems, a mobile station (MS) is able to move around an area in which multiple cells are defined. Each cell is served by a base station. The base stations use the same carrier frequency for their transmissions, and so these transmissions are identified by means of code signals which are transmitted by the base stations.
In order to establish a connection with a base station, a mobile station must go through an acquisition procedure. This requires that the mobile station be synchronised to the base station. This synchronisation is achieved by means of a matched filter. The maximum length of this filter is set by the frequency deviation which may exist between the base station and the mobile station, and so the length of the filter is restricted.
When the mobile station has established a connection with a base station, it must then continue to make measurements on signals received from other base stations. Again, the mobile station must synchronise to the other base stations before making these measurements. However, at this stage, the restricted length of the matched filter increases the time taken to synchronise to the base stations.
EP-0884856 describes a system of this type, in which the speed of acquisition is sought to be increased by using multiple matched filters.